To shed some light on Ali's question, I've decided to re-print and rewrite portions of last year's article to give it a more modern taste.  The article begins with a brief processor history, starting with Intel's Pentium 1 processor.  The end of the article is followed by a comparison-overview chart to better explain the differences in Front Side Bus (FSB) speed which can have a dramatic effect on the overall performance of a computer system.

Without further adieu, here it is:

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Intel Processor History: starting with the Pentium 1

In 1993, Intel brought the PC to a new level with the Pentium processor. The first Pentium processor ran at an astounding 60 Mhz, had 3.3 million transistors, and performed 100 Million Instructions Per Second (MIPS). Although no one today refers to the first Pentium processor as a Pentium 1, it is the original of 4 types of Pentium processors developed by Intel.

The Pentium 2 and the Celeron

Once the first Pentium processor technology became obsolete, the Pentium 2 was introduced. Starting at 233 MHz, the Pentium 2 took over its sibling's footsteps and was designed to run from 233 MHz to 450 Mhz. At about the same time, the Intel Celeron processor was presented; it was identical to the Pentium 2 except it was considered a "lower end" processor because of two main differences: a smaller cache and a slower bus speed, also known as the Front Side Bus or FSB speed rating*.

* Cache memory is a special part of the processor which helps to process frequently used information faster.  FSB is the speed that the processor communicates with all other peripherals inside the computer.  FSB speed can have a profound influence on the overall speed of a computer.  For example: Pentium 2 processors ran a 100 MHz Front Side Bus, compared to lower-end Celerons which operated at 66 MHz.

The Pentium 3

Not too long after the introduction of the Celeron, the first Pentium 3 processor replaced the Pentium 2 and ran at 450 MHz.  The Pentium 3 bus was first rated at 100 MHz but then increased to 133 MHz beginning with the 500 MHz model processor -- also known as the "500EB" model.

The AMD Athlon Processor

Even though AMD has been around for quite some time, AMD's popularity did not come into the spotlight until the introduction of the Athlon processor. At around the same time that Intel introduced their 600 MHz Pentium 3 processors, AMD wowed the world with the Athlon processor.

The Athlon processor not only ran programs just as well as the Intel Pentium 3 and its predecessors, but its bus speed also ran twice as fast as the Pentium 3. AMD's groundbreaking technology utilized a dual front side bus, even though the raw processing speed (or MHz rating) was the same as Intel's Pentium 3 or Celeron processors.

The AMD Duron

AMD became a success story with the Athlon processor and, like Intel, began producing a lower cost processor -- the AMD Duron -- which also had less cache.

At this time, the Celeron's FSB ran at a mere 66 MHz while the Duron boasted a 200 MHz bus.  This gave consumers an excellent value for their money, considering that the Duron was much cheaper than a Celeron.

The Duron processor is set to cease production in 2003, when it will be replaced by a newer model, called the Opteron.

The Pentium 4

The Pentium 3 ended its reign at 1400 MHz (or 1.4 GHz) and has been replaced by its bigger brother, the Pentium 4.  The Intel Celeron processors are still in production today, reaching speeds up to 2200 MHz and beyond (December, 2002), with an amazing 400 MHz Front Side Bus.  The current Pentium 4 processor breaks the 3000 MHz (or 3 GHz) barrier and has an impressive Front Side Bus of 533 MHz.

Today's Processors: the AMD Athlon XP vs the Intel Pentium 4

Not too long ago, AMD introduced their new line of Athlon processor: the Athlon XP. While still an Athlon processor, the Athlon XP does not use the conventional MHz rating to depict its speed.

AMD believes that a MHz rating would undermine its true performance and therefore wishes to change public perception. For those who insist of raw MHz numbers, AMD claims a 25% performance increase of their XP 1900+ compared to a Pentium 4 running at 1900 Mhz.

The AMD Athlon XP speed rating calculation

Information about how to calculate the raw MHz speed rating of an AMD Athlon XP processor was discussed in a previous newsletter, dated August 22, 2002.  In brief:

If you remember how to "solve for x" using High School math, AMD's speed rating can be calculated.  The variable X can represent the MHz rating using the below generic formula:

MHz = (XP rating/1.5) + (500/1.5)

For example, using the 1800+ processor QuantiSpeed rating:

MHz = (1800+/1.5) + (500/1.5)

MHz = 1200 + ~333.33333333...

MHz = ~1533.33

The squiggly ~ means "approximately."  Since .333 is infinitely repeated, it's just nice way to represent "short form."

More bang for the buck?

Quite simply said: the AMD Athlon XP processor runs very close to an Intel Pentium 4 processor and is about half the price.  RDR RAM, which is used in a Pentium 4 machine, is roughly double the price of DDR RAM used in a AMD Athlon XP machine.  Comparably so, RDR RAM runs faster than does DDR RAM: 533 MHz compared to 333 MHz FSB (December, 2002).

Intel has a much larger market share than AMD and has had plenty of time to build a solid public image.  Intel also aggressively advertises their processors, which might explain why they are about double the price of their major competitor, AMD.

An overview of speed and FSB ratings

The below chart provides a clear picture of processors and their corresponding Front Side Bus ratings.  The information in this article represents the majority of Intel and AMD processors, up until December, 2002: